Low liquid level control device



A. T. BRowNE LOW LIQUID LEVEL CONTROLl DEVICE 'Filed'mg. 11, 1967 N N N N N N N N N NhNNNN April vl, 1969 United States Patent O 3,435,731 LOW LIQUID LEVEL CONTROL DEVICE Andrew T. Browne, Globe Hoist Company, Salisbury, Md. 21801 Filed Aug. 11, 1967, Ser. No. 659,987 Int. Cl. F1Sb 21/04 U.S. Cl. 91-4 10 Claims ABSTRACT OF THE DISCLOSURE Low liquid level control device for a semi-hydraulic lift having a ring-shaped float mounted about the air line. The float seals the space about the air line when the liquid level is too low. A flow deilecting bushing is attached to the bottom of the plunger between the air line and the opening for laterally diverting the iluid flowing upwardly through the opening to minimize fuming.

Background of the invention The opening or ilow passage in an oil control device for a semi-hydraulic lift also provides a passageway for returning the oil from the cylinder to within the hollow plunger. When the plunger is lowered, the returning oil jets upwardly through the passageway with considerable force and is likely to lill the space within the plunger and surrounding atmosphere with oil fumes. These fumes are annoying and explosive to the extent of creating a safety hazard. Such a system is described in U.S. Patents 3,237,- 523 and 3,140,641. The latter patent describes a baille intended for preventing such fuming. This baille is however disposed above the level of the liquid at the critical phase when the plunger just starts to lower and the oil level within it is at its low point.

An object of this invention is to provide a means for minimizing fuming within the plunger of a semi-hydraulic lift having a low oil level control device.

Another object is to provide such a means which is particularly useful in conjunction Vwith such a device having a iloat mounted about the air line.

Summary In accordance with this invention a ilow delecting bushing is connected to the bottom plate of the plunger. The discharge portion of the flow passage through the bushing is laterally oriented within the plunger to divert the upwardly jetting oil laterally within the bottom of the plunger. This prevents the jet of oil flowing into the plunger from breaking the liquid surface and furning. The bushing may be secured to the bottom plate of the plunger between its upper and lower flanges. The upper flange may help close the space between the air line and the bottom plate by its engagement with an inner circular lip within the bottom of the float.

Brief description of the drawings Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a cross-sectional front view in elevation of one embodiment of this invention in the lowered position;

FIG. 2 is a view similar to FIG. 1 in the raised position under low oil conditions;

FIG. 3 is an enlarged cross-sectional view in elevation of a portion of FIG. 2;

FIG. 4 is a cross-sectional view in elevation of a portion of the embodiment shown in FIG. 1 as the plunger is being lowered;

3,435,731 Patented Apr. 1, 1969 ICC Description of the preferred embodiment In FIGS. 1-6 is shown a low oil control device 10 mounted within hollow plunger 12 of semi-hydraulic lift 14. In such a semi-hydraulic lift the raising and lowering of hollow plunger 12 is accomplished by introducing and withdrawing air through air line 16 into the space 18 within hollow plunger 12. In the lowered condition of plunger 12 shown in FIG. l, air has been exhausted from space 18 to cause oil 20 to ilow into substantially all of space 18 thus causing plunger 12 to sink to the bottom of cylinder 22.

As more clearly shown in enlarged FIGS. 3 and 5, device 10 includes a tubular or ring-shaped member 24 having a tubular buoyant section 26, made for example of urethane foam, and a lower sealing section 28 of a resilient deformable material, such as rubber. Sealing section 28 may thus be made of a Buna N or neoprene type rubber. Section 28 includes a circular foot 30 which engages sealing surface 32 in bottom plate 34 of hollow plunger 12. Sealing surface 32 is, for example, machined into the top of bottom plate 34 of hollow plunger 12. Sealing section 28 also includes an inner circular lip 36 for engaging circular sealing ridge 38 in the top ilange 40 of ilow-deilecting bushing 42.

Flow-dellecting bushing 42, made of a durable material, such as strong plastic, also includes a central sleeveshaped section 44 inserted within opening 46 between air line 16 and bottom plate 34. Bushing 42 is secured to bottom plate 34 between upper ilange 40 and lower ilange 48 of bushing 42. Bushing 42 is assembled by passing tabs 50 connected to central section 44 through slots 52 in lower end ilange 48 and forming a head 54 on the protruding ends of tabs 50 by heat sealing. Bushing 42 may also be made of metal and secured by peening or soldering.

Liquid or oil 20 passes upwardly through passageway 46 in the space between hole 47 in bottom plate 34 of plunger 12 and through radial passageways 56 in upper flange 40 and radial passageways 58 in lower ilange 48 as shown in FIG. 6. Radial passageways 56 in upper ilange 40 comprise discharge passageways which (as shown in FIGS. 4 and 5) laterally deflect oil passing upwardly through them laterally along the direction of arrows 59 towards the sides of hollow plunger 12. This confines the oil or liquid jets within liquid or oil 20 in the bottom of plunger 12 to cause the resultant turbulence to prevent the oil from jetting upwardly through the surface of the oil 20. The operating condition shown in FIG. 4 is the most critical under normal operations because the liquid level is than at its low point. This prevents annoying and dangerous oil fumes from filling space 18 and exhausting into the interior of the service area.

Retaining ring assembly 60 shown in FIGS. l and 2 at the top of air line 16 prevents member 24 from being forced upwardly off the end of air line 16 during extreme conditions of operation.

As shown in FIG. 5, a ring type seal 62 is inserted between bushing 42 and air line 16 to minimize the amount of liquid flowing therebetween. Seal 62 is for example a quad-ring seal. This seal is not absolutely necessary for eective operation of the flow-dellecting device of this invention but it can be used to prevent any oil from ilowing upwardly around the air line. This ilow deilector may also be used in conjunction with a low oil control device of the type described in U.S. Patent 3,237,523, which seals to the air line and the Ibottom of the plunger instead of that shown herein which seals to the bushing surrounding the air line and to the bottom plate of plunger 12.

What is claimed is:

1. A low liquid level control device for a semihy draulic lift including an air line and a hollow plunger having a bottom plate immersed in a liquid, an opening in said bottom plate, said air line extending upwardly within said plunger through said opening for introducing air pressure within said plunger above the level of said liquid, said device comprising a substantially ring-shaped buoyant member mounted about said air line to freely move up and down relative to said air line, a lower surface of said buoyant member being large enough in radial dimension and made to seal to the periphery of said opening, circular closure means between said air line and said member for sealing the space therebetween to cause said member to prevent said liquid from flowing through said opening when said lower surface of said member is sealed to the periphery of said opening, a flowdeflecting bushing connected to said bottom plate, said bushing being constructed and arranged to slide in substantially close proximity to the outside of said air line whereby said fluid is substantially diverted to flow between said bushing and said periphery of said opening, said bushing having a flow passage extending through it from below to above said bottom plate, and said flow passage having a discharge portion above said bottom plate which is laterally oriented whereby it diverts liquid owing upwardly through it laterally within said bottom of said plunger to minimize fuming within said plunger.

2. A device as set forth in claim 1 wherein a ring type sealing means is inserted between said bushing and said air line for minimizing the amount of liquid flowing therebetween.

3. A device as set forth in claim 2 wherein said ring type sealing means comprises a sealing ring, a circular recess within a portion of said bushing, and said sealing ring being inserted within said recess in sliding sealing engagement with said air line.

4. A device as set forth in claim 2 wherein said circular closure means comprises a circular surface upon a portion of said bushing disposed within said hollow plunger and a coresponding circular mating surface upon said buoyant .member which is in sealing engagement with said circular surface when said lower surface of said buoyant member is sealed to the periphery of said opening.

5. A device as set forth in claim 3 wherein said buoyant member comprises a tubular buoyant section and a lower sealing section, said sealing section being deformable and resilient, said sealing section including a circular foot for engaging said periphery of said opening, and said sealing section also including a circular inner lip which comprises said corresponding circular mating surface for engaging said circular surface upon said bushing.

6. A device as set forth in claim 1 wherein said flowdeflecting bushing comprises an upper end tiange within said hollow plunger, a sleeve-shaped central portion extending through said bottom plate, a lower end ange disposed outside of said hollow plunger, said flanges being disposed upon opposite sides of said bottom plate of said hollow plunger for securing said bushing to said bottom plate, and said upper end flange having radial flow passages for accomplishing said lateral diversion of said liquid.

7. A device as set forth in claim 6 wherein said lower end flange also has radial ow passages.

8. A device as set forth in claim 6 wherein said central sleeve-shaped portion has an outer dimension smaller than said opening whereby said liquid is channeled therebetween.

9. A device as set forth in claim 8 wherein one of said end flanges is separate from the remainder of said bushing, and fastening means attaches said separate end flange to said bushing for assembling it to said bottom plate.

10. A device as set forth in claim 1 wherein a retaining ring is secured to an upper portion of said air line for limiting the upward movement of said buoyant member.

References Cited UNITED STATES PATENTS 2,637,302 5/ 1953 Harrison et al. 91-4 2,970,577 2/ 1961 Sinclair 91-4 3,140,641 7/ 1964 Clarke et al. 91-4 3,179,014 4/ 1965 Hott et al. 91-4 3,237,523 3/ 1966 Wallace 91-4 EDGAR W. GEOGHEGAN, Primary Examiner. 

